1. Field of the Invention
The present invention relates to an electromagnetic actuator that generates a driving force by an electromagnetic force, and, more particularly, relates to an electromagnetic actuator used when a shutter blade or a diaphragm blade of a camera is driven to rotate within a predetermined angular range, and relates to a camera blade driving device that is driven by the electromagnetic actuator and is provided with a shutter blade used to block all light passing through an exposure opening or a diaphragm blade used to block part of the light.
2. Description of the Related Art
In order to drive a shutter blade or a diaphragm blade, a conventional electromagnetic actuator mounted in a camera-blade-driving device, such as a camera shutter device or a camera diaphragm device, is made up of a rotor 2 supported rotatably with respect to a base 1 having an exposure opening 1a, a lower yoke 3 and an upper yoke 4 that have magnetic pole portions disposed to face an outer peripheral surface of the rotor 2, a bobbin 6 around which a coil 5 is wound, a presser plate 7 for holding down the lower yoke 3 and upper yoke 4 and rotatably supporting the rotor 2, and screws 8 by which the presser plate 7 is fastened to the base 1, as shown in FIG. 1.
In order to assemble the electromagnetic actuator, the rotor 2 is first attached rotatably to a supporting shaft 1b of the base 1. Next, linear parts 3a and 4a are then inserted into an engagement hole 6a of the bobbin 6 while laying the lower yoke 3 and upper yoke 4 on each other, and the bobbin 6 around which the coil 5 is wound is incorporated thereinto so as to form a module.
Thereafter, this modularized component is fixed to a predetermined position of the base 1, the presser plate 7 is then placed thereon, the screw 8 is then screwed to a screw hole 1c of the base 1, and the presser plate 7 is fastened to the base 1. Thus, the electromagnetic actuator serving as a driving source in the camera blade driving device is completely incorporated thereinto (Japanese Unexamined Patent Publication No. 2002-156684, for example).
Furthermore, in the electromagnetic actuator constructed as mentioned above, the lower yoke 3 and upper yoke 4 are attached to the bobbin 6, and, after that, the whole is fixed by use of the presser plate 7 that has been formed as an independent part. Therefore, the assembly task is complex, and the number of components is large, thereby causing an increase in component management costs, in manufacturing costs, etc.
The present invention has been made in consideration of the problems of the conventional technique. It is therefore an object of the present invention to provide an electromagnetic actuator capable of reducing the number of components, capable of simplifying the assembly task, capable of reducing costs, capable of simplifying a structure, etc., and to provide a camera blade driving device that includes a shutter blade or a diaphragm blade driven by this electromagnetic actuator.
An electromagnetic actuator of the present invention that achieves the object has a rotor magnetized to have a plurality of poles, a base rotatably supporting the rotor, a yoke having a plurality of magnetic pole portions that are formed so as to face an outer peripheral surface of the rotor and that generate different magnetic poles, a magnetizing coil, and a bobbin/presser member which is disposed on an outer periphery of the yoke, around which the coil is wound, and with which a pressing portion for pressing the yoke against the base and for supporting the rotor is formed integrally.
According to this structure, since the bobbin and the pressing portion are formed integrally with each other, the parts count is reduced, and, proportionally thereto, man-hours or labor hours to handle the components can be saved, an assembly task can be simplified, and costs can be lowered.
In the electromagnetic actuator constructed as mentioned above, the yoke may have two magnetic pole portions and be shaped substantially like a xe2x80x9cUxe2x80x9d including a straight part that has one of the two magnetic pole portions at its end, and the bobbin may have an engagement hole into which the straight part is fitted.
According to this structure, after the yoke is inserted into the engagement hole of the bobbin so as to be united together, the united pieces can be positioned and fixed directly to the base. Therefore, assembling time (step) can be saved, and the assembly task can be more easily performed than in the conventional manner in which the constituent parts formed individually are positioned and fixed individually to the base.
In the electromagnetic actuator constructed as mentioned above, the pressing portion may be formed so as to extend from both ends of the bobbin.
According to this structure, since the pressing portion is fixed to the base at both sides between which the bobbin is placed, they can be firmly assembled while the parts count is reduced or the assembly task is simplified.
In the electromagnetic actuator constructed as mentioned above, the pressing portion may be formed so as to extend from one end of the bobbin.
According to this structure, the bobbin/presser member that unitedly has the bobbin and the pressing portion can be reduced in size, can be simplified in structure, and can be reduced in weight.
A second electromagnetic actuator of the present invention that achieves the object has a base, a rotor rotatably supported by the base and magnetized to have a plurality of poles, a nearly U-shaped yoke disposed on the base so as to face an outer peripheral surface of the rotor, a magnetizing coil, and a bobbin including a portion around which the coil disposed on one side of the yoke is wound and a portion holding the yoke and the rotor so as not to fall off the base.
According to this structure, the bobbin around which the coil is wound holds the yoke and the rotor so as not to fall off the base. Therefore, the parts count is reduced, and proportionally thereto, man-hours or labor hours to handle the components can be saved, an assembly task can be simplified, and costs can be lowered.
A camera blade driving device of the present invention that achieves the object has a base having an exposure opening, a shutter blade that is rotatably supported by the base and that opens and closes the opening, and an electromagnetic actuator including a rotor that is magnetized to have a plurality of poles and that is rotatably supported by the base, a yoke having a plurality of magnetic pole portions that are formed to face an outer peripheral surface of the rotor and that generate different magnetic poles, a magnetizing coil, and a bobbin/presser member which is disposed on an outer periphery of the yoke, around which the coil is wound, and with which a pressing portion for pressing the yoke against the base and for supporting the rotor is formed integrally, the electromagnetic actuator driving the shutter blade.
According to this structure, since the bobbin and the pressing portion of the electromagnetic actuator that drives the shutter blade are formed integrally with each other, and since the single base supports the rotor and the shutter blade, the parts count is reduced, and, proportionally thereto, the man-hours or labor hours to handle the components can be saved, the assembly task can be simplified, the structure can be simplified, and device costs can be lowered.
In the camera blade driving device constructed as mentioned above, the yoke may have two magnetic pole portions and be shaped substantially like a xe2x80x9cUxe2x80x9d including a straight part that has one of the two magnetic pole portions at its end, and the bobbin may have an engagement hole into which the straight part is fitted.
According to this structure, after the yoke is inserted into the engagement hole of the bobbin so as to be united together, the united pieces can be positioned and fixed directly to the base. Therefore, assembling time (step) can be saved, and the assembly task can be more easily performed than in the conventional manner in which the constituent parts formed individually are positioned and fixed individually to the base.
In the camera blade driving device constructed as mentioned above, the pressing portion may be formed so as to extend from both ends of the bobbin.
According to this structure, since the pressing portion is fixed to the base at both sides between which the bobbin is placed, they can be firmly assembled while the parts count is reduced or the assembly task is simplified.
In the camera blade driving device constructed as mentioned above, the pressing portion may be formed so as to extend from one end of the bobbin.
According to this structure, the bobbin/presser member that unitedly has the bobbin and the pressing portion can be reduced in size, can be simplified in structure, and can be reduced in weight.
A second camera blade driving device of the present invention that achieves the object has a base having an exposure opening, a diaphragm blade that is rotatably supported by the base and that adjusts (or limits) the amount of light passing through the opening, and an electromagnetic actuator including a rotor that is magnetized to have a plurality of poles and that is rotatably supported by the base, a yoke having a plurality of magnetic pole portions that are formed to face an outer peripheral surface of the rotor and that generate different magnetic poles, a magnetizing coil, and a bobbin/presser member which is disposed on an outer periphery of the yoke, around which the coil is wound, and with which a pressing portion for pressing the yoke against the base and for supporting the rotor is formed integrally, the electromagnetic actuator driving the diaphragm blade.
According to this structure, since the bobbin and the pressing portion of the electromagnetic actuator that drives the diaphragm blade are formed integrally with each other, and since the single base supports the rotor and the diaphragm blade, the parts count is reduced, and, proportionally thereto, the man-hours or labor hours to handle the components can be saved, an assembly task can be simplified, the structure can be simplified, and device costs can be lowered.
In the second camera blade driving device constructed as mentioned above, the yoke may have two magnetic pole portions and be shaped substantially like a xe2x80x9cUxe2x80x9d including a straight part that has one of the two magnetic pole portions at its end, and the bobbin may have an engagement hole into which the straight part is fitted, and the diaphragm blade may have a blade that defines an aperture with a predetermined hole diameter and an ND filter that is joined to the blade so as to cover at least this aperture and by which the amount of light is reduced.
According to this structure, after the yoke is inserted into the engagement hole of the bobbin so as to be united together, the united pieces can be positioned and fixed directly to the base. Therefore, assembling time (step) can be saved, and the assembly task can be more easily performed than in the conventional manner in which the constituent parts formed individually are positioned and fixed individually to the base.
When the diaphragm blade is driven by the electromagnetic actuator and is caused to face the opening, if the aperture is greater than the exposure opening, the amount of light passing through the opening is reduced only by the operation of the ND filter, and, if the aperture is a diaphragm aperture smaller than the exposure opening, the amount of light passing through the opening can be reduced both by the operation of the diaphragm aperture and by the operation of the ND filter.
In the second camera blade driving device constructed as mentioned above, the diaphragm blade may have a pair of blades, and the ND filter may be joined while being placed between the pair of blades.
According to this structure, since a layered structure exists in which the ND filter is placed between the pair of blades, the mechanical strength of the diaphragm blade can be increased, and the ND filter can be prevented from being scratched.
In the second camera blade driving device constructed as mentioned above, the ND filter may be joined to a surface on one side of the blade.
According to this structure, since the ND filter is merely joined so as to cover at least the aperture, the diaphragm blade can be reduced in weight and in thickness, and, accordingly, the device can be thinned.
In the second camera blade driving device constructed as mentioned above, the yoke may have two magnetic pole portions and be shaped substantially like a xe2x80x9cUxe2x80x9d including a straight part that has one of the two magnetic pole portions at its end, and the bobbin may have an engagement hole into which the straight part is fitted, and the diaphragm blade may have a diaphragm aperture smaller in hole diameter than the exposure opening.
According to this structure, after the yoke is inserted into the engagement hole of the bobbin so as to be united together, the united pieces can be positioned and fixed directly to the base. Therefore, assembling time (step) can be saved, and the assembly task can be more easily performed than in the conventional manner in which the constituent parts formed individually are positioned and fixed individually to the base. Furthermore, when the diaphragm blade is driven by the electromagnetic actuator and is caused to face the opening, the amount of light passing through the opening can be reduced by the diaphragm aperture.
In the second camera blade driving device constructed as mentioned above, the pressing portion may be formed so as to extend from both ends of the bobbin.
According to this structure, since the pressing portion is fixed to the base at both sides between which the bobbin is placed, they can be firmly assembled while the parts count is reduced or the assembly task is simplified.